Mix and sift flour, baking powder and salt. Cream butter, add sugar slowly and cream until fluffy. Stir in well-beaten egg yolks and vanilla extract. Add sifted dry ingredients alternately with the cream. Chill for one hour, roll and cut in any desired shape. Sprinkle with sugar before baking. Bake in a moderate oven (350 or 375 degrees) for 10 to 12 minutes
